1. Cross Reference to Related Applications
This application is related to co-pending applications, two of which are entitled “In-plane field type transflective liquid crystal display device,” and one of which is entitled “Transflective liquid crystal display device,” and all of which are assigned to the same assignee as this application.
2. Field of the Invention
The present invention relates to liquid crystal displays (LCDs), and more particularly to an in-plane field type reflective liquid crystal display device having at least one extraordinary type polarizer.
3. Description of the Prior Art
Due to the features of being thin and consuming little power, liquid crystal display devices have been used in a broad range of fields. Applications include office automation (OA) apparatuses such as word processors and personal computers, portable information apparatuses such as portable electronic schedulers, videocassette recorders (VCRs) provided with information panels, and mobile phones provided with liquid crystal monitors.
Unlike with a cathode ray tube (CRT) display or an electroluminescence (EL) display, the liquid crystal display screen of a liquid crystal display device does not emit light itself. Instead, in a conventional transmission type liquid crystal display device, an illuminator called a backlight is provided at a rear or one side of the liquid crystal display device. The amount of light received from the backlight which passes through the liquid crystal panel is controlled by the liquid crystal panel, in order to provide images for display.
In the transmission type liquid crystal display device, the backlight consumes 50% or more of the total power consumed by the liquid crystal display device. That is, the backlight is a major contributor to power consumption.
In order to overcome the above problem, a reflection type liquid crystal display device (“RLCD”) has been developed for portable information apparatuses which are often used outdoors or in places where artificial ambient light is available. The reflection type liquid crystal display device is provided with a reflector formed on one of a pair of substrates, instead of having a backlight. Ambient light is reflected from a surface of the reflector to illuminate the display screen. However, the RLCD still has an inherent drawback that cannot be eliminated; namely, a very narrow viewing angle. By adding one or more compensation films on the RLCD, this problem can be ameliorated to some extent. However, the extra components increase costs proportionately.
In addition, because a polarizer used in the RLCD is made of PVA, it cannot work at temperatures higher than 80 degrees Centigrade. This limits the kinds of application environments in which the RLCD can be used. Furthermore, because the polarizer is positioned as an outer surface of the RLCD, it is easily damaged or even destroyed in handling or in use. Moreover, in manufacturing of the RLCD, the polarizer is typically a separate part having protecting films. In the last step of manufacturing, the polarizer is adhered on the RLCD panel. This makes the RLCD unduly thick and bulky.
It is desired to provide an in-plane switching type reflective liquid crystal display device which overcomes the above-described deficiencies.